I looked in the core book but I couldn't find it. The index points to page 92 but I don't see what the actual MPH is. I get that CoD is not necessarily a stats-heavy game but I'd like something to go off of if some moves at 4, someone else moves at 4x4 or 10x4.
Speed wasn’t changed in the Rules update for CoD, so I will refer you back to p. 95 of the 2004 rulebook.
“Your character’s Speed represents the number of yards she can move in a turn and still perform an action.”
“Alternatively she can run up to double her Speed in a turn, but can usually take no other action.”
There is an example in that section where the character has a Speed of 9 which means she can jog 9 yards or run 18 in a turn.
The length of time for a turn is 3 seconds (p. 37).
So there are 1200 turns in an hour. Each dot of speed allows you to jog 1200/1760 mph (0.68 mph) or run 2400/1760 mph (1.36 mph).
That puts a fairly average human character with a speed of 9 being able to run about 12 mph over a short burst.
In combat, creatures move at (Speed x 1.2) km/h walking, (Speed x 2.4) km/h running
This is covered on page 26 of the Chronicles of Darkness core rulebook, and it differs from the first (World of Darkness) edition because they’ve embraced the metric system:
A character’s speed is equal to Strength + Dexterity + 5. A character can move this many meters in one turn.
As per page 73 of the same book, a turn lasts three seconds:
Turn — The smallest increment of time, a turn lasts for about three seconds.
And on page 92, in the combat rules:
A character can move his Speed in a single turn and still take an instant action. He can give up his action to move at double his normal Speed.
Thus a Speed of 1 translates to a walking speed of 0.33m/s (metres per second), equal to 1.2km/h (kilometres per hour) or a bit less than 0.75mph (miles per hour).
This means an average human character with a speed of 9 has a walking speed of 3m/s, or 10.8km/h (6.7mph). That’s higher than the usual average adult walking speed of around 5 or 6 km/h, but we’re only measuring it this precisely in combat, so it makes sense people are moving quicker.
If they run, the average human can cover 18m in 3 seconds. That’s a short burst speed of 21.6 km/h (13.4 mph).
Peak human speed from an athlete with Strength and Dexterity ratings of 5 would be 10 m/s, or 36km/h (22.3mph). That’s quite a bit slower than the official world record - Usain Bolt ran 100 metres in under 10 seconds, reaching a speed of 44.6km/h (27.8mph) - but realistic given we’re measuring speed during a combat scenario, not a foot race. (CoD has a nice abstract system for chases.)
Of course, dedicated sprinters may have merits like Fleet of Foot to further boost their speed. Fleet of Foot 3 would raise the human maximum speed to 43.2 km/h which is pretty close to the real world record.